Ti:sapphire-pumped high repetition rate femtosecond optical parametric oscillator
TL;DR: A broadly tunable femtosecond optical parametric oscillator (OPO) based on KTiOPO(4) that is externally pumped by a self-mode-locked Ti:sapphire laser is described.
Abstract: A broadly tunable femtosecond optical parametric oscillator (OPO) based on KTiOPO4 is externally pumped by a self-mode-locked Ti:sapphire laser. The laser is capable of continuous tuning from 1.2 micrometers to 1.37 micrometers in the signal branch and 1.8 to 2.15 micrometers in the idler branch, when using one set of OPO optics. Other optics expand the tuning range of the OPO from 1.0 micrometers to 2.75 micrometers, for example, by using three sets of mirrors and two different crystals. Without prisms in the OPO cavity, 215 mW of chirped pulses is generated in the signal branch, while 235 mW is generated in the idler branch. The total conversion efficiency, as measured by pump depletion, is 50%. With prisms in the cavity, nearly transform-limited pulses of 135 femtoseconds are generated, which can be shortened to 75 fs by increasing the output coupling.
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TL;DR: In this paper, the authors summarized the recent progress in the development of ultrafast optical parametric amplifiers, giving the basic design principles for different frequency ranges and in addition presenting some advanced designs for the generation of ultrabroadband, few-optical-cycle pulses.
Abstract: Over the last decade there have been spectacular developments in ultrafast laser technology, due to the introduction of solid state active materials and of new mode-locking and amplification techniques. These advances, together with the discovery of new nonlinear optical crystals, have fostered the introduction of ultrafast optical parametric amplifiers as a practical source of femtosecond pulses tunable across the visible and infrared spectral ranges. This article summarizes the recent progress in the development of ultrafast optical parametric amplifiers, giving the basic design principles for different frequency ranges and in addition presenting some advanced designs for the generation of ultrabroadband, few-optical-cycle pulses. Finally, we also briefly discuss the possibility of applying parametric amplification schemes to large-scale, petawatt-level systems.
914 citations
TL;DR: The working principles of new, nonlinear laser microscopies based on two‐photon molecular excitation are described, specifically, Imaging of vital DNA stains in developing cells and embryos, imaging of cellular metabolic activity from NADH autofluorescence, spatially resolved measurements of cytoplasmic calcium ion activity, and optically induced micropharmacology using caged bioeffector molecules.
Abstract: With the development of sensitive and specific fluorescent indicators, modern laser scanning microscopies enable visualization and measurement of submicron, dynamic processes inside living cells and tissues. Here we describe the working principles of new, nonlinear laser microscopies based on two-photon molecular excitation. In these techniques, a pulsed laser produces peak photon densities high enough that when focused into an appropriate medium, excitation by photon energy combinations can occur. For example, two red photons interacting simultaneously with a fluorescent molecule can excite within it a UV electronic transition, one corresponding to twice the energy of each single photon. Because the amount of two-photon excitation depends on the square of the local illumination intensity, this process exhibits a unique localization to the diffraction-limited spot of the beam focus. Elsewhere along the beam, excitation of background and photodamage is virtually nonexistent. Focal point localization of two-photon excitation lends to all visualization, measurement, and photopharmacology studies an intrinsic, three-dimensional resolution. We describe some preliminary biological applications, specifically, imaging of vital DNA stains in developing cells and embryos, imaging of cellular metabolic activity from NADH autofluorescence, spatially resolved measurements of cytoplasmic calcium ion activity, and optically induced micropharmacology using caged bioeffector molecules.
265 citations
TL;DR: By exploiting nonlinear optical effects, a technology of unprecedented flexibility for the production of tunable coherent light has been developed that provides sources with spectral coverage extending all the way from the ultraviolet to the mid-infrared and temporal coverage extending over all time domains.
Abstract: By exploiting nonlinear optical effects, a technology of unprecedented flexibility for the production of tunable coherent light has been developed. Referred to as optical parametric generation, it provides sources with spectral coverage extending all the way from the ultraviolet to the mid-infrared, and with temporal coverage extending over all time domains from the femtosecond pulse to the continuous wave. Such sources generate coherent light of outstanding optical quality and are now finding wide-ranging applications.
255 citations
TL;DR: The recent advances in imaging at the macro- and micro-scale are described and how these advances are synergistic with new imaging agents, reporters, and labeling schemes are described in the context of cancer progression and metastasis.
Abstract: Imaging has become an indispensable tool in the study of cancer biology and in clinical prognosis and treatment. The rapid advances in high resolution fluorescent imaging at single cell level and MR/PET/CT image registration, combined with new molecular probes of cell types and metabolic states, will allow the physical scales imaged by each to be bridged. This holds the promise of translation of basic science insights at the single cell level to clinical application. In this article, we describe the recent advances in imaging at the macro- and micro-scale and how these advances are synergistic with new imaging agents, reporters, and labeling schemes. Examples of new insights derived from the different scales of imaging and relevant probes are discussed in the context of cancer progression and metastasis.
227 citations
TL;DR: P pulses tunable in the 590-666-nm range are produced, with durations down to 13 fs, using an 82-MHz Ti:sapphire second-harmonic-pumped, high-bandwidth, beta-barium borate optical parametric oscillator in a fused-silica prism group-delay-dispersion-compensated, six-mirror folded ring cavity.
Abstract: We have produced pulses tunable in the 590-666-nm range, with durations down to 13 fs, using an 82-MHz Ti:sapphire second-harmonic-pumped, high-bandwidth, beta-barium borate optical parametric oscillator in a fused-silica prism group-delay-dispersion-compensated, six-mirror folded ring cavity.
225 citations
References
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TL;DR: Pulses having durations as short as 60 fsec have been directly generated by a self-mode-locked, dispersion-compensated Ti:sapphire laser and by using an extracavity fiber-prism pulse compressor.
Abstract: Pulses having durations as short as 60 fsec have been directly generated by a self-mode-locked, dispersion-compensated Ti:sapphire laser. By using an extracavity fiber-prism pulse compressor, pulse durations as short as 45 fsec have been obtained.
1,487 citations
Patent•
14 Jul 1989TL;DR: In this paper, a femtosecond optical parametric generator with a nonlinear crystal cut from the group CTA and RTA for noncritical phasematching is presented.
Abstract: A broadly tunable femtosecond optical parametric generator includes a cavity having a pumping section in which is located a nonlinear crystal selected from the group CTA and RTA, cut for noncritical phasematching. The plane of the optical x axis and or the optical y axis of the crystal is aligned with the axis of the pumping section. A Ti:S laser pumping beam is directed into the pumping section either collinearly or noncollinearly with the pumping section axis and impinges on the crystal to produce signal and idler beams. The laser is tunable to produce OPO output beams between about 1 and 4 μm.
344 citations
TL;DR: In this paper, a tunable, singley-resonant optical parametric oscillator provides femtosecond light pulses in the infrared wavelength band, including an internally mounted thin crystal of KTiOPO 4 which is synchronously pumped by femto-cond pulses from a colliding-pulse passively mode-locked dye laser.
Abstract: A tunable, singley-resonant optical parametric oscillator provides femtosecond light pulses in the infrared wavelength band. The oscillator includes an internally mounted thin crystal of KTiOPO 4 which is synchronously pumped by femtosecond pulses from a colliding-pulse passively mode-locked dye laser. Rotation of the crystal varies the wavelength of the oscillator. Prisms within the oscillator cavity control group velocity dispersion to limit pulse width, and the oscillator as stabilized by a feedback network which varies the length of the cavity in response to spectral changes.
237 citations
TL;DR: Dispersion compensation of a cw mode-locked optical parametric oscillator based on a thin crystal of KTiOPO4 pumped intracavity by a standard colliding-pulse mode-lock dye laser is described and transform-limited pulses should be possible throughout the tuning range.
Abstract: We describe dispersion compensation of a cw mode-locked optical parametric oscillator based on a thin crystal of KTiOPO4 pumped intracavity by a standard colliding-pulse mode-locked dye laser, The device provides potential cw tunability from 0.72 to 4.5 μm with milliwatt outputs. Transform-limited pulses should be possible throughout the tuning range;here we report pulse widths of 105 fsec at 840 nm and 108 Hz. Active stabilization of the oscillator cavity is also discussed.
97 citations
TL;DR: In this article, a nonlinear differential equation describing a synchronously pumped, singly resonant optical parametric oscillator is derived, which accounts for the important effects associated with this kind of ultrashort tunable-pulse generation, including the effects of phase mismatch, pulse walkoff, group-velocity dispersion, cavity-length detuning, and pump depletion.
Abstract: A single nonlinear differential equation describing a cw synchronously pumped, singly resonant optical parametric oscillator is derived. This equation accounts for the important effects associated with this kind of ultrashort tunable-pulse generation, including the effects of phase mismatch, pulse walk-off, group-velocity dispersion, cavity-length detuning, and pump depletion. The various effects are investigated in detail through numerical solutions. The formalism is general enough that the results obtained are applicable to a wide variety of systems.
94 citations